338 ^'EAV EXGLAXD TREES IX AVIXTEE. 



Key to Oaks based upon fruiting material. 



109. Fruit maturing in autumn of second year, ripe acorns therefi.ire 

 borne upon parts of twig two years old; immature acorns to be 

 round in winter on twigs of the past season's growth; shell of 

 nut hairy inside; abortive ovules at the top of the nut; scales 



of acorn-cup broad and thin; lobes of lea\"es bristle-pointed 



Black Oaks 110 



109. Fruit maturing in one j'ear. ripe acorns therefore borne upon past 

 seasons gro'U'th; no immature acorns to be found upon t wig's in 

 ■n-inter; shell of nut smooth inside; abortive ovules at base of nut; 

 lower scales at least of acorn cup more or less thickened at base 

 giving a knobby appearance to surface of cup: scales more or less 

 densely "^'ooUj'; kernel commonly s'U'eetish; lobes of leaves n<it 



bristle-pointed: bark flaky except in Chestnut Oak 



Mhite Oaks 114 



Cup of acorn shallow saucer-shaped Ill 



Cup top- shaped 112 



Cu]! thin. 15 mm. or less ^vide: biuls 1 mm. rir less long 



I'iii Ojik iQiimcus iJaiustrisj p. 448 



Cup thi(:k, 20 mm. or more wide; buds ov^-r 4 mm. long 



Red Oak (Qucrcus ruhra)pA4G 



Buds under 4 mm. long: twigs slender; shrubs 



Hear «.>ak iQurrri'S iUcifoJia ip.4't4 



Buds 0"\"er 4,5 mm. long; fu'igs rather stuut; trees llli 



E'pper scales of cup loosely overlapping; buds pointed, whole 

 surface woolly; inner bark yellow. BUiok Oak iQjtercus velutina V'-^'*' 

 Upper scales of cup closely o\"erlapp,ing; buds blunt, downy above 

 middle; inner bark pale red. Scarlet Oak iQucrcua coccinea) p. 450 



Upper scales of cup with thread-like outgrowths forming a 

 fringe to cup; branchlets often with corky ridges; lateral buds 



frequently appressed Bur Onk (Quercus macrocarpa) p.43« 



Cup without distinct fringe; branchlets without corky ridgesj 

 lateral buds divergent 115 



115. Bark on branchlets peeling back in dark stiff-papery layers; 

 marginal si-ales "t cup n irrow a wn-pi>in[<r-d ; acorns long-stalked. 

 Swamp AVIiite Oak (Quercus bico^OfV p.43S 



115. Bark on branchlets not peeling back in dark stiff-papery layers; 

 acorns sessile or short-.'^talked (at times long- stalked in White 

 Oak) 116 



116. Buds sharp-pointed 11' 



116. Buds blunt US 



117. Xut 20-35 mm. long; buds 4-10 mm. long; bark thick, furrowed. 

 Hilt flaky C'lieslmit 0"ak (Que}'CHS Prinus)pA44 



117. Xut 15-20 mm. lung; buds :-'!-6 mm. long; bark thin, flaky 



Cliiu<iu«piii Oak (Quercus Muhlenhergiijp.440 



lis. Twigs slender, generally ni't over 2 mm. thick; shrubs 



0«arf Chiiiiniapiu Oak (Quercus prinoideslp.44'2 



lis. Twigs relatively stout, generally ox'er 2 mm. thick; trees .... lli" 



119. Twigs, at least in part, covered with very fine close olive-green 

 di iwn ; buds, generally nearly hemispheiiral. about as broad as 

 I'.uig: scales of cup only slightly knobby, apex of nut generally 

 d<.\vn>- Post Oak (Quercus stellata) p.4;i4 



119. Twigs smooth ; buds distinctly hmger tlian broad, broadly ovate; 

 scabs of cup thirk-knobby at base, aiicx of nut generally smooth. 

 A\'liitc Oak (Qntrcus alba J p.4.i'2 



Key to Oaks without fruit. 



NOTE. ( "W I after name indicates that the tree belongs to the White 

 Oak Group. 

 ( B ) after name indicates that the tree belongs to the Black 

 '_>ak Group. 

 Immature acrns thnrefiire may often be fi-und on winter twigs of 

 S]icfies marked with (B) but not on those marked with (W). 



120. Buds large, those at tip of twig 4..". mm. or more b-uig 121 



120. Buds smaller, less than 4.5 mr 



